Method of adjusting power output of a reflex klystron employing movable permanent magnets and a reflex klystron with movable magnets for adjusting power output



y 1969 J. w. ROMMERTS ETAL 3,444,420

METHOD OF ADJUSTING POWER OUTPUT OF A REFLEX KLYSTRON EMPLOYING MOVEABLE PERMANENT MAGNETS AND A REFLEX KLYSTRON WITH MOVEABLE MAGNETS FOR ADJUSTING POWER OUTPUT Filed April 18, 1966 JAN W.ROMMERTS T HOMAS J.WEST ERHOF BY lNVENTOR- I. a

3,444,420 METHOD OF ADJUSTING POWER OUTPUT OF A REFLEX KLYSTRON EMPLOYING MOVABLE PERMANENT MAGNETS AND A REFLEX KLYS- TRON WITH MOVABLE MAGNETS FOR AD- JUSTING POWER OUTPUT Jan Willem Rommerts and Thomas Jan Westerhof, Em-

masingel, Eindhoven, Netherlands, assignors, by mesne assignments, to US. Philips Corporation, New York, N.Y., a corporation of Delaware Filed Apr. 18, 1966, Ser. No. 543,119 Claims priority, application Netherlands, Apr. 23, 1965, 6505165 Int. Cl. H01j 25/22 US. Cl. 3155.18 6 Claims ABSTRACT OF THE DISCLOSURE A reflex klystron is provided with permanent magnets movable in external guides to adjust the klystron for maximum power output.

The invention relates to a method of adjusting an electron tube having an electrostatically concentrated, velocity-modulated electron flow to maximum output power and particularly of a reflex klystron having fixedly arranged electrodes suitable for wavelengths of less than 1 cm. (frequencies of more than 30,000 mc./s.).

In general, the electrodes of such tubes have so far been arranged so that with the aid of mechanical means they could be slightly displaced in a radial direction during the test of the tube. The electrodes were adjusted so that the tube delivered the maximum output power.

Since such adjustable structures are complicated and expensive and tend to produce microphony, it has been suggested that the electrode be arranged immovably. Particularly with wavelengths below 10 mm., very high requirements have to be met by the mechanical machining and mounting, so that the percentage of rejects was high.

It has been found that, if the electrodes are accurately positioned symmetrically about the center line, a maximum current distribution between the cathode and the reflector is obtained; however, they have to deviate slightly from this position in order to attain the maximum output power, the direction of deviation being different for each tube. Deviations due to mechanical inaccuracies will, in general, not correspond exactly to the deviation required for the maximum output power. Since with a fixed electrode arrangement the mechanical adjustment can no longer be varied after mounting, a high percentage of rejects is involved. Furthermore, satisfactory operation depends not only upon an accurate machining but also upon a vary accurate mounting operation. Moreover, the tube cannot be adjusted to maximum output power, since during mounting the required deviation from the symmetrical arrangement cannot be taken into account.

In a method of adjusting to maximum output power of such an electron tube having an electrostatically concentrated, velocity-modulated electron flow and comprising fixedly arranged electrodes these difficulties can be completely avoided, if in accordance with the invention during the test of the tube a correcting magnetic field is produced in the neighborhood of the electrode system by means of one or more correction magnets so that the output power of the tube is at a maximum, after which the correction magnet, or magnets, is, or are, definitely secured to the tube.

Since such tubes operate at high voltages, they are always surrounded by a generally metallic screening sheath to protect them from contact. It is advantageous to arrange the correction magnets according to the invention in narrow channels of this screen and definitely fixed in the correct position after the tube is adjusted to maximum output power. The magnets may be fixed to the tube wall in a different way, for example in the space between the tube bulb and the envelope. In this case they must be displaceable or rotatable from the outside.

The invention will be described more fully with reference to the drawing, in which FIG. 1 shows diagrammatically a sectional view and FIG. 2 a plan view of an embodiment of a tube according to the invention.

Referring to the figures, reference numeral 1 designates a glass envelope, accommodating a reflex klystron system, shown diagrammatically and consisting of an electron gun 2, a reflector 3 and an apertured cavity resonator anode 4, through which passes an electrostatically concentrated, velocity-modulated electron flow 5.

The envelope 1 is surrounded by an envelope 6 of nonmagnetic material. The cavity resonator 4 joins a wave pipe, which includes a tuning piston 7. At the level of the electrode system the envelope 6 has a thickened portion 8, which may be rectangular and which is provided with narrow channels 9. The envelope is preferably made of copper or aluminum, but it may be made of an insulating material, for example ceramic or synthetic resin.

During the test of the tube a rod-shaped magnet 10 is introduced into one of the channels 9 or in more channels to a depth such that the output power is at a maximum, after which it is fixed in the correct position by means of, for example screws, soldering material or cement 11. By means of these magnets mechanical deviations of the electrode and of the arrangement thereof can be corrected, so that the tolerances in manufacture and mounting may be considerably greater.

The magnets 10 need not be arranged parallel to the tube axis; they may occupy any experimentally determined position. However, mechanically the provision of channels 9 parallel to the axis is the simplest method. By means of the four channels 9 and the adjustment of the place of the magnets in the channels 9 any desired correction can be made for attaining the maximum output power.

If desired, a plurality of magnets may be accommodated in one channel. The portion 8 of the sheath need not be rectangular; it may have a cylindrical shape.

It is found that by using the method according to the invention the output power can be raised by about 20%, with a wavelength of 8 mm. as compared with a corresponding tube having electrodes arranged accurately symmetrically relative to the axis of the beam.

While the invention has been described with reference to particular examples and embodiments thereof, other modifications will be apparent to those skilled in this art without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

1. A method of adjusting to maximum power output an electron discharge tube having an electrode system and an electrostatically concentrated, velocity-modulated electron flow comprising the steps of placing a plurality of magnets in proximity to the tube to produce a magnetic field in the vicinity of the electrode system, moving the magnets relative to the electrode in a direction perpendicular to the path of electron flow to positions at which the output power of the tube is at a maximum, and fixedly positioning said magnets at the position of maximum power output.

2. A klystron having a magnetic system for producing a maximum power output comprising an envelope containing an electrode system for producing an electro- 4 statically concentrated velocity-modulated electron flow, References Cited a second envelope surrounding said first envelope, said UNITED STATES PATENTS second envelope having a channel therein substantlally perpendicular to the path of electron flow in the first 2,789,249 4/1957 Jams envelope in which a plurality of magnets can be moved 5 2,823,334 2/1958 Lebwtet 315-522 for producing a magnetic field in the vicinity of the 2,909,691 10/1959 Hell X electrode system Within the first envelope, and means 340461439 7/1962 Houston fixedly positioning said magnets in a position for maximum power output of said klystron. FOREIGN PATENTS 3. A klystron as claimed in claim 2 in which the chan- 10 1,344,615 10/1963 F nel is formed in an enlarged portion of the second enve ope HERMAN KARL SAALBACH, Primary Examiner.

4. A klystron as claimed in claim 2 in which the magnets are fixed in Position with so1der SAXFIELD CHATMON, 111., Asszstant Exammer.

5. A klystron as claimed in claim 2 in which the mag- 15 nets are fixed in position with cement.

6. A klystron as claimed in claim 2 in which the magnets are fixed in position with adjustable members.

US. Cl. X.R. 33184 

